A drive force of an actuator or the like can be used for opening/closing of a valve of an engine or as a motion force of another member. In this case, an operational rod to which the drive force of the actuator or the like is outputted and a motion member of a motion mechanism utilizing this drive force are coupled with each other. Regarding this coupling arrangement, Patent Document 1 discloses a valve shaft driving apparatus for use in an operational mechanism of a variable intake valve provided in an intake manifold of an automobile. The variable intake valve is mounted within an intake passage to be pivotally opened/closed, thereby to change the intake air flow speed for improvement of combustion of the engine. The coupling arrangement of Patent Document 1 includes an actuator having an operational rod advanced or retracted along the axial direction, a lever member (a motion member) provided in a valve shaft of a valve that opens/closes a passage and a pin member (a shaft portion) provided in the lever member and inserted in and coupled with a shaft hole of the operational rod. A bearing member is provided along the periphery of the pin member. As a stopper ring is fitted to the end of the pin member, inadvertent withdrawal of the operational rod is prevented. Advancing and retracting movements of the operational rod are transmitted from the pin member to the lever member to be converted into rotational drives of the valve.